Understand How a Pointer to Structure is Returned from a Function

/*
Write a program to understand how a pointer to structure is returned from a function 
*/

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
struct student {
        char name[20];
        int rollno;
        int marks;
           };
void display(struct student *);
struct student *func( );
struct student *ptr;
main( )
{
    struct student *stuptr;
    stuptr = func( );
    display(stuptr);
    free(stuptr);
}
struct student *func( )
{
    ptr = (struct student *) malloc(sizeof(struct student) );
    strcpy( ptr->name, "Joseph");
    ptr->rollno = 15;
    ptr->marks = 98;
    return ptr;
}
void display( struct student *stuptr)
{
    printf("Name  - %s\t", stuptr->name);
    printf("Rollno  - %d\t", stuptr->rollno);
    printf("Marks  - %d\n", stuptr->marks);
}